Combinatorics : GMAT Quantitative Section
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 21 Jan 2017, 20:08

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Combinatorics

Author Message
TAGS:

### Hide Tags

Intern
Status: Applying for PhD
Affiliations: University of Peshawar
Joined: 21 Mar 2013
Posts: 4
Location: Pakistan
Concentration: Strategy, Marketing
Schools: HBS '15
GMAT Date: 07-31-2013
GPA: 3.4
WE: Education (Education)
Followers: 0

Kudos [?]: 9 [3] , given: 0

### Show Tags

19 Aug 2013, 12:47
3
KUDOS
1
This post was
BOOKMARKED
Here is a schematic presentation of how Combinatorics work.

First, Does the order in which thing are done (or items are selected) matter in this question. If the answer is yes than its a Permutation problem. If the answer is no than it's a Combination problem.

Now when you have determined whether it's a combination or a permutation problem ask yourself the second question, is repeated selection allowed in this problem?
If "r" is the number of choices to be made and "n" is the total number of choices allowed than use the appropriate formula.

Permutation with repetition: n^r
Permutation without repetition: n!/(n-r)!
Combination with repetition: (n+r-1)/r!(n-r)!
Combination without repetition: n!/r!(n-r)!

Hope it helps, will try to add more detailed explanation with time. (Check the attachment and kindly give your feedback and suggestion).
Attachments

Combinatorics.jpg [ 182.39 KiB | Viewed 1434 times ]

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13490
Followers: 576

Kudos [?]: 163 [0], given: 0

### Show Tags

17 Jul 2015, 04:37
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Combinatorics   [#permalink] 17 Jul 2015, 04:37
Similar topics Replies Last post
Similar
Topics:
1 Combinatorics: Anagram 1 23 Jul 2015, 02:20
1 PS Combinatorics 5 24 Apr 2013, 13:11
7 Combinatorics Summary 7 29 Jan 2012, 22:28
Probability and Combinatorics 3 20 Apr 2010, 09:02
195 Math: Combinatorics 38 27 Nov 2009, 10:05
Display posts from previous: Sort by